init

lib/forum/network.ex

@@ -0,0 +1,161 @@
+defmodule Forum.Network do
+  @moduledoc """
+  A per-network process for serving the app's forms view.
+
+  Requests to `/` use the root forms. Requests to `/<network>` use the
+  matching network forms from `priv/networks/<network>/index.html`.
+  """
+  use GenServer
+
+  @default_hosts MapSet.new(["localhost", "127.0.0.1", "0.0.0.0", ""])
+
+  def child_spec(opts) do
+    slug = opts |> Keyword.fetch!(:slug) |> normalize_slug()
+
+    %{
+      id: {:network, slug},
+      start: {__MODULE__, :start_link, [[slug: slug]]},
+      restart: :permanent,
+      shutdown: 5_000,
+      type: :worker
+    }
+  end
+
+  def start_link(opts) do
+    slug = Keyword.fetch!(opts, :slug)
+    GenServer.start_link(__MODULE__, slug, name: via(slug))
+  end
+
+  def normalize_slug(slug) when is_binary(slug) do
+    slug
+    |> String.downcase()
+    |> String.split(":", parts: 2)
+    |> hd()
+  end
+
+  def serve(pid, request) do
+    GenServer.call(pid, {:serve, request})
+  end
+
+  @impl true
+  def init(slug) do
+    {:ok, %{slug: normalize_slug(slug), root: site_root(slug), started_at: DateTime.utc_now()}}
+  end
+
+  @impl true
+  def handle_call({:serve, request}, _from, state) do
+    response = do_serve(state, request)
+    {:reply, response, state}
+  end
+
+  defp do_serve(%{slug: slug} = state, request) do
+    path = Map.fetch!(request, :path)
+
+    cond do
+      default_site?(slug) and path in ["", "/"] ->
+        desktop_response()
+
+      network_site?(slug) and path in ["", "/"] ->
+        network_forms_response(slug)
+
+      File.dir?(state.root) ->
+        static_response(state.root, path)
+
+      true ->
+        %{
+          status: 404,
+          content_type: "text/plain",
+          body:
+            "No network configured for #{slug}. Create files under #{Path.relative_to_cwd(state.root)}."
+        }
+    end
+  end
+
+  defp desktop_response do
+    body =
+      Forum.Assets.path("ui/desktop.html")
+      |> File.read!()
+      |> String.replace("<!-- FORMS_HTML -->", Forum.Forms.html())
+
+    %{status: 200, content_type: "text/html", body: body}
+  end
+
+  defp network_forms_response(slug) do
+    body =
+      Forum.Assets.path("ui/desktop.html")
+      |> File.read!()
+      |> String.replace("<!-- FORMS_HTML -->", Forum.Forms.html(slug))
+
+    %{status: 200, content_type: "text/html", body: body}
+  end
+
+  defp static_response(root, path) do
+    file_path = resolve_path(root, path)
+
+    cond do
+      file_path == :invalid ->
+        %{status: 403, content_type: "text/plain", body: "Forbidden"}
+
+      File.dir?(file_path) and File.regular?(Path.join(file_path, "index.html")) ->
+        send_file(Path.join(file_path, "index.html"))
+
+      File.regular?(file_path) ->
+        send_file(file_path)
+
+      true ->
+        %{status: 404, content_type: "text/plain", body: "Not found"}
+    end
+  end
+
+  defp resolve_path(root, path) do
+    relative =
+      path
+      |> String.trim_leading("/")
+      |> URI.decode()
+
+    candidate = Path.expand(relative, root)
+    rel_to_root = Path.relative_to(candidate, Path.expand(root))
+
+    if rel_to_root == ".." or String.starts_with?(rel_to_root, "../") do
+      :invalid
+    else
+      candidate
+    end
+  end
+
+  defp send_file(path) do
+    %{status: 200, content_type: content_type(path), body: File.read!(path)}
+  end
+
+  defp content_type(path) do
+    case Path.extname(path) do
+      ".html" -> "text/html"
+      ".css" -> "text/css"
+      ".js" -> "application/javascript"
+      ".json" -> "application/json"
+      ".svg" -> "image/svg+xml"
+      ".png" -> "image/png"
+      ".jpg" -> "image/jpeg"
+      ".jpeg" -> "image/jpeg"
+      ".webp" -> "image/webp"
+      ".gif" -> "image/gif"
+      ".ico" -> "image/x-icon"
+      ".txt" -> "text/plain"
+      _ -> "application/octet-stream"
+    end
+  end
+
+  defp site_root(slug) do
+    source_path = Path.expand(Path.join(["priv", "networks", normalize_slug(slug)]), File.cwd!())
+
+    if File.exists?(source_path) do
+      source_path
+    else
+      Application.app_dir(:forum, Path.join(["priv", "networks", normalize_slug(slug)]))
+    end
+  end
+
+  defp default_site?(slug), do: MapSet.member?(@default_hosts, slug)
+  defp network_site?(slug), do: slug in Forum.Networks.network_slugs()
+  defp via(slug), do: {:via, Registry, {Forum.ProcessRegistry, {:network, normalize_slug(slug)}}}
+end